(57) In a reactor coolant circulating pump (18) having an outer casing (24) and a rotor (32) rotatably mounted in said casing (24), characterized by an assembly (52) for facilitating inspection of said pump rotor (32), comprising means defining a cylindrical bore (60) through said casing (24) in axial alignment with an end (32A) of said pump rotor (32); an extension (62) on said rotor end (32A) and rotatable therewith, said extension (62) including a cylindrical coupler member (70) extending into said bore (60) and having an outer end (70B) with an element (74,76) configured to receive a tool (78,80) for performance of inservice rotor inspection; a hollow cylindrical member (64) disposed in said bore (60) and surrounding said coupler member (70), said cylindrical member (64) being slidably movable relative to said coupler member (70) along said bore (60) between a retracted position wherein said cylindrical member (64) is stored for normal pump operation and an extended position wherein said cylindrical member (64) is in sealing engagement with said casing (24) and said extension (62); and a cover member (68) sealably attached to said casing (24) across said bore (60) for closing said bore (60) and retaining said cylindrical member (64) in its retracted position for normal pump operation, said cover member (68) being detachable from said casing (24) for opening said bore (60) and allowing movement of the cylindrical member (64) to its extended position to permit inservice rotor inspection.